What makes the lifestyle and genome of Nanoarchaeum equitans unique?

 N. equitans is the only identified intracellular parasite within the Archaea. It lives within the periplasm of Ignicoccus. N. equitans depends upon its host for the biosynthesis of many essential amino acids and cofactors and may not even be able to make its own ATP. The genome of N. equitans, is one of the smallest ever described and is the smallest among Archaea. It is also the most dense genome, with over 95% of the genome predicted to encode for proteins. Based on the genes that are missing from the genome, N. equitans may depend on Ignococcus for both carbon and energy. The key enzymes for DNA repair, DNA replication, transcription, and translation are present in N. equitans genome.

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